Gas burner for furnaces and the like



Oct 3 v c. A. REICHELDERFER ETAL 3,532,452

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ATTORNEYS United States Patent O 3,532,452 GAS BURNER FOR FURNACES AND THE LIKE Charles A. Reichelderfer, Harrisonburg, and Frederick L. Runninger, Rockingham County, Va., assignors to Dunham-Bush, Inc., a corporation of Delaware Filed June 21, 1968, Ser. No. 738,920 Int. Cl. F23m 9/00 US. Cl. 431185 Claims ABSTRACT OF THE DISCLOSURE A gas-fired burner having a cylindrical casing and rings therein, together with a flame-retaining cone member at its discharge orifice, relatively positioned to form pressurized air and gaseous fuel into a discharge stream formed of an inner nonswirling inner stream, an intermediate rapidly swirling stream, and an outer nonswirling stream enveloping the inner and intermediate streams and inclined inwardly toward the principal axis of the discharge streams.

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates in general to a burner of improved design for firing compact furnaces having relatively restricted combustion space, and more particularly to a burner of small size designed to burn natural gas for firing in heat exchangers of the type disclosed in the copending application Ser. No. 720,719, filed Apr. 11, 1968, by Charles A. Reichelderfer, one of the joint inventors of the present application.

Many difficulties have been encountered in attempting to design low cost burners of small size for burning natural gas in furnaces. It is desirable that such burners provide reliable operation without pulsation in a small combustion space at higher than atmospheric pressure and with a very small stable flame. Such burners should provide quiet complete combustion with minimum excess air, they should burn the natural gas at a predetermined rate and require a minimum of adjustment for optimum performance, they should not be dependent upon the geometric configuration of the combustion zone, and desirably should provide long life without deterioration of parts. Preferably, the burner should be easily ignited from a low energy electric spark, and should be of such design as to be suitable for monitoring by an electronic flame detector.

An object of the present invention, therefore, is the provision of a novel, low cost burner designed to burn natural gas at a predetermined rate, and which is small in size so as to be usable for firing compact furnaces having relatively restricted combustion space.

Another object of the present invention is the provision of a novel burner as described in the immediately preceding paragraph, which will be reliable in operation without pulsation in a small combustion space at higher than atmospheric pressure, and produce a very small stable flame.

Yet another object of the present invention is the provision of a novel burner of the type described in the preceding paragraphs, which provides quiet, complete combustion with minimum excess air and which provides the desired performance characteristics independent of the geometric configuration of the combustion zone.

Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating one preferred embodiment of the invention.

3,532,452 Patented Oct. 6, 1970 BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a fragmentary perspective view of the burner of the present invention, mounted on a heat exchanger in the upper portion of a hot air furnace structure;

FIG. 2 is a vertical section view through the burner, taken along the line 22 of FIG. 1;

FIG. 3 is a vertical section through a portion of the burner, taken along the line 3-3 of FIG. 2, and

FIG. 4 is an elevation view of the discharge end of the burner, as viewed from the right hand side of FIG 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION While the burner assembly of the present invention is usable in many different types of furnaces or with many different types of heat exchangers, it will be described in conjunction with a hot air furnace of the type disclosed in the previously identified patent application of Charles A. Reichelderfer, Ser. No. 720,719. Referring to the drawings wherein like reference characters designate corresponding parts throughout the several figures, and particularly to FIG. 1, wherein the burner of the present invention, generally indicated by the reference character 10, is shown in solid lines and the associated furnace components are shown in broken lines, the burner assembly 10 is shown mounted against one of the walls of a heat exchanger 11 of generally box-like or cube configuration located in an upper space 12 of the furnace 13 defined by the horizontal partition 14 and the walls of the furnace casing 15. In the particular furnace herein illustrated, a blower 16 driven by a motor 17 is mounted in the lower compartment of the furnace casing below the partition 14 to draw return air through an inlet connection (not shown) and discharge the air into the space 12 above the partition 14 through the outlet opening 16a provided in the partition and forming the discharge opening of the blower scroll.

The burner assembly 10 includes a generally vertical mounting plate 18 attached in a suitable manner to the front wall 11a of the heat exchanger, as by a gas-tight flange joint, in covering relation to a burner inlet opening in the front wall 11a of the heat exchanger and extending downwardly to abut the horizontal partition 14. A space 19 is provided between the partition 14 and the lower wall 11b of the heat exchanger for free flow of pressurized air below the heat exchanger from the discharge opening 16a of the blower 16 to the air inlet opening 20 in the lower region of the mounting plate 18. The mounting plate 18 supports an air inlet plenum or inlet manifold 21 which receive the air for combustion, in the described embodiment, from the space 19 and blower 16. Thus, in this embodiment, the combustion air for the burner is supplied under pressure from the same blower supplying circulating air to the furnace. However, it will be understood that the air for combustion entering the intake manifold 21 may, if desired, be supplied by directly connecting the intake manifold 21 to an atmospheric source for combustion air, for furnaces equipped with induced draft means, or, alternatively, a separate blower for combustion air only could be used for supplying forced draft combustion air to the inlet manifold 21. Above the inlet manifold 21 is the generally cylindrical firing head and fiame retainer structure generally indicated at 22 and formed of a plurality of coaxial, generally cylindrical hollow rings or sleeves, including the casing cylinders 23, the valve sleeve 24 and progressively inwardly spaced ring members 25, 26 and 27. The innermost ring members 26 and 27 are joined together at their front and rear edges to define an annular gas chamber or manifold 28 therebetween to which the gas is supplied by a fuel supply tube 29. This gaseous fuel is discharged into an inner, substantially cylindrical air port or chamber 30 through orifices 28a and into an intermediate air port or chamber 31 through orifices 28b.

The forced draft combustion air in the inlet manifold 21 passes through fixed orifice 23a in the lower wall portion of the casing cylinder 23 and through the orifice 24a in the rotatable valve sleeve 24 into the annular air chamber 32 defined between the casing cylinder 23 and the outer ring 25. An external locking screw 33 fixed to the rotatable valve sleeve 24 and extending through an arcuate slot in the casing cylinder 23 provides acessible means for adjusting the position of the orifice 24a in relation to the orifice 23a. After entering the annular air chamber 32, the combustion air flows to the front or exterior wall 34 of the burner and divides into two streams, due to the inward spacing of the front edges of ring members 25 and 26 from the front wall 34, one stream entering the intermediate annular air port 31 and the other stream entering the inner air port 30. After mixing with gas injected through the ports 28a, the air in the inner port 30 flowing into the combustion zone is divided into two coaxial streams. The center stream does not swirl, but the outer stream forming the boundary layer or stream adjacent the innermost ring member 27 enters the combustion zone in a rotation condition due to the radially innermost portions of slots 35 adjacent the hollow center opening 36a of a truncated, flame-retaining cone 36 mounted at the discharge or combustion end of the subassembly 22, as by securing the same to the joined rear edges of the inner ring members 26 and 27.

The combustion air flowing through the intermediate annular air port 31 is divided into two streams after mixing with gas from the orifices 28b. The outer of these two streams enters the combustion zone in a non-swirling manner by passing through the outer annular orifice 37 formed in the shape of an uninterrupted ring between the outer periphery of the flame-retaining cone 36 and the inwardly constricting or truncated conical portion 23b of the casing cylinder 23, this outermost stream being directed toward the center of the flame by the inwardly constricting casing cylinder portion 23b. The inner stream of air and fuel flowing through the intermediate port 31 passes through the slots 35 in flame-retaining cone 36 and is caused to rotate by the configuration of these slots so as to enter the combustion zone in a swirling manner, and thus joins the outer portion of the air from the port 30 to form a single rotating stream flowing coaxially between two nonrotating streams. The slots 35 are constructed by uniformly, alternately, inwardly and outwardly bending or forming the edges of radial slots cut in the truncated conical section of the cone 36. The angles of the inwardly formed edges 38a and outwardly formed edges 38b determine the slot width and the extent of swirling of the fluid passing through the cone 36.

From the above description it will be apparent that the burner introduces into the combustion zone, through the upper opening 39 in mounting plate 18, three streams of mixed air and fuel gas in a very compact manner which causes rapid mixing of these streams within the combustion zone. The innermost stream, passing through the center opening 36a in the flame-retaining cone 36, is small in diameter and not whirling. The intermediate hollow stream, formed by the outer air stream from the inner port 30 and the inner air stream discharged from the intermediate port 31, both of which pass through the slots 35 in the flame-retaining cone 36, whirls rapidly, due to the direction imparted to the fluid by the slots 35. The enveloping outer hollow stream passing through the uninterrupted outer annular orifice 37 is not whirling, but is restrained from expanding by the inward direction imparted by the conical, inwardly constricted portion 23b of the casing cylinder 23. This arrangement of two controlled, non-swirling streams tightly enveloping a rapidly whirling stream produces most intimate mixing of fuel and air and causes combustion to be completed in a minimum of space. The flat surfaces between the slots 35 on the inner face of the cone 36 (that surface of the cone which faces toward the combustion zone), create areas of relatively low pressure which impede the forward velocity of the flame, thereby giving the cone excellent flame-retention characteristics. Ignition may be initiated by an electric discharge across the electrodes, such as the electrodes indicated at 40 in FIG. 2. Presence of flame may be detected by any one of several well known devices which cause the gas flow to be shut off if. ignition is not detected within a predetermined safe period, or may be visually observed through a transparent window 41 provided in the front wall 34 of the burner.

While but one specific embodiment of the present invention has been particularly shown and described, it will be apparent that various modifications may be made therein within the spirit and scope of the invention, and it is desired, therefore, that only such limitations be placed thereon as are imposed by the prior art and set forth in the appended claims.

What is claimed is:

1. A gas-fired burner structure comprising a substantially cylindrical casing extending along an axis and hav ing an open discharge end to be disposed adjacent a combustion zone and a closed end, fuel inlet means for supplying gaseous fuel into said casing, air inlet means for supplying pressurized air into said casing to form an air and fuel gas mixture at a selected mixing zone therein, a truncated conical annulus within said casing adjacent said open end wherein the conical walls thereof diverge toward said open end and said annulus having a center opening and fluid directing slot formations in the surrounding annular portion thereof, a plurality of radially spaced partition rings within said casing concentric with said axis and spaced from said closed end between the latter and said annulus coactive with said annulus to form the air and fuel gas mixture discharged from within said casing through said open end into a first inner, nonswirling discharge stream surrounded by a second rapidly swirling stream and a third nonswirling outer annular stream enveloping the first and second streams and directed in paths converging inwardly toward said axis, and said selected mixing zone where the air and gas are intermixed being located upstream toward said closed end from the region where said streams are formed whereby each of the streams is formed of the air and fuel gas mixture.

2. A gas-fired burner structure, as defined in claim 1, wherein said partition rings include a pair of ring members joined together to form a substantially closed annular fuel chamber connected to said fuel inlet means and located to divide air flowing in said casing into a first substantially cylindrical stream flowing axially away from said closed end and a second outwardly surrounding annular stream flowing in the same direction as and spaced from said first stream by said fuel chamber, and said joined pair of ring members having orifices for directing fuel gas into both of said first and second streams.

3. A gas-fired burner structure as defined in claim 2, wherein the innermost one of said joined pair of ring members defines a cylindrical inner chamber for passage of said first stream therethrough, and said center opening of said conical annulus is of smaller diameter than said cylindrical inner chamber, the outermost portion of said first stream passing through said slot formations and being formed thereby into a swirling stream of air and gas mixture surrounding the stream of nonswirling fluid which passes through said center opening.

4. A gas-fired burner structure as defined in claim 3, wherein the outer periphery of said conical annulus is spaced radially inwardly from said casing at said open end defining an annular space therebetween and projects partially into intercepting relation to said second stream, the radially inner portion of said second stream being formed by said slot formations into a swirling discharge stream which joins the swirling stream formed from said first stream and the radially outer portion of said second stream passing through said annular space and forming a nonswirling annular stream surrounding said swirling streams.

5. A gas-fired burner structure as defined in claim 4, wherein said casing has an inwardly constricted, truncated conical portion immediately adjacent said open end for directing said nonswirling annular stream in inwardly inclined relation to said axis toward a selected flame region spaced externally of the casing along said axis from said open end. H

6. A gas-fired burner structure as defined in claim 1, wherein said casing has an inwardly constricted, truncated conical portion immediately adjacent said open end for directing said third nonswirling annular stream in inwardly inclined relation to said axis toward a selected flame region spaced externally of the casing along said axis from said open end.

7. A gas-fired burner structure comprising a substantially cylindrical casing extending along an axis and having an open discharge end to be disposed adjacent a combustion zone and a closed end, fuel inlet means for supplying gaseous fuel into said casing, air inlet means for supplying pressurized air into said casing to form an air and fuel gas mixture therein, a truncated conical annulus within said casing adjacent said open end having a center opening and having fluid directing slot formations in the surrounding annular portion thereof, a plurality of radially spaced partition rings within said casing concentric with said axis and spaced from said closed end between the latter and said annulus coactive with said annulus to form the air and fuel gas mixture discharged from within said casing through said open end into a first inner, nonswirling discharge stream surrounded by a second rapidly swirling stream and a third nonswirling outer annular stream enveloping the first and second streams and directed in paths converging inwardly toward said axis, said partition rings including a pair of ring members joined together along their circumferential edges to form a substantially closed annular gaseous fuel chamber connected to said fuel inlet means and an outermost ring member spaced radially outwardly from said joined pair of ring members and joined to said casing adjacent said open end, the air supplied to said casing by said air inlet means being introduced outwardly of said outermost ring member to pass toward said closed end and then be split into a first inner cylindrical stream directed toward said discharge end and bounded by the innermost of said joined pair of ring members and a second annular stream directed toward said discharge end and located between said joined pair of ring members and said outermost ring member, and said pair of ring members having orifices for directing fuel gas inwardly and outwardly into said first and second streams.

8. A gas-fired burner structure as defined in claim 7, wherein said casing has an inwardly constricted, truncated conical portion immediately adjacent said open end for directing said third nonswirling annular stream in inwardly inclined relation to said axis toward a selected flame region spaced externally of the casing along said axis from said open end.

9. A gas-fired burner structure comprising a substantially cylindrical casing extending along an axis and having an open discharge end to be disposed adjacent a combustion zone and a closed end, fuel inlet means for supplying gaseous fuel into said casing, air inlet means for supplying pressurized air into said casing to form an air and fuel gas mixture therein, a truncated conical annulus within said casing adjacent said open end having a center opening and having fluid directing slot formations in the surrounding annular portion thereof, a plurality of radially spaced partition rings within said casing concentric with said axis and spaced from said closed end between the latter and said annulus coactive with said annulus to form the air and fuel gas mixture discharged from within said casing through said open end into a first inner, nonswirling discharge stream surrounded by a second rapidly swirling stream and a third nonswirling outer annular stream enveloping the first and second streams and directed in paths converging inwardly toward said axis, said casing including a cylindrical wall having an air inlet opening therein, an air supply chamber adjoining said cylindrical wall and communicating with the interior of said casing through said air inlet opening, and a cylindrical sleeve member inwardly abutting said cylindrical wall for rotation about said axis relative to said wall and having an opening therein conforming substantially to said air inlet opening to be positioned in variable lapping relation to said air inlet opening for varying the air supply to said casing.

10. A gas-fired burner structure as defined in claim 5, wherein said casing includes a cylindrical wall having an air inlet opening therein, an air supply chamber adjoining said cylindrical wall and communicating with the interior of said casing through said air inlet opening, and a cylindrical sleeve member inwardly abutting said cylindrical wall for rotation about said axis relative to said wall and having an opening therein conforming substantially to said aid inlet opening to be positioned in variable lapping relation to said air inlet opening for varying the air supply to said casing.

References Cited UNITED STATES PATENTS 1,661,031 2/1928 Butcher 431-183 1,991,894 2/1935' Forney 431-185 3,266,549 8/1966 Wolfersperger 431-9 3,302,684 2/1967 Banko 431183 EDWARD G. FAVORS, Primary Examiner 

